As an electric power steering device of this type, there has been known an electric power steering device configured in such a manner that a control circuit unit having a power element therein for driving a motor, in a casing, on a housing of a motor for assisting a steering force of the steering wheel. Lead wires connected to the power element in the control circuit unit are connected through a trunk wire via openings arranged at the housing and casing to the motor coil (for example, see Patent Document 1).
Likewise, Patent Documents 2 to 4 also describe the configuration in which a control device for controlling the motor is mounted on the motor and a terminal of the motor is connected to that of the control device.
Meanwhile, there has also been known the configuration in which the electric motor for transmitting the steering assist force to the steering shaft is coupled through the reduction gear mechanism in the reduction gearbox to the steering shaft, so that the control unit for controlling the electric motor is mounted in the reduction gearbox (for example, see Patent Document 5).